1. Field of the Invention
The present invention relates to method and apparatus for transmitting video signals having a plurality of aspect ratios, such as movie software or the like.
2. Description of the Prior Art
Movies for theaters employ, in addition to a standard size picture having an aspect ratio of 4:3, a variety of picture systems such as an European Vista Vision (registered trademark) size picture having an aspect ratio of 1.66:1, an American Vista Vision size pictures having an aspect ratio of 1.85:1, a 70-mm size picture having an aspect ratio of 2.18:1, a Cinema Scope (registered trademark) size picture having an aspect ratio of 2.35:1 or the like. When such movie for theaters is converted into a present video signal having an aspect ratio of 4:3 (=1.33:1), a so-called letter box system is used, in which right and left portions of a reproduced picture are made coincident with right and left portions of a picture screen and black portions (shown hatched) are provided on the upper and lower portions of the picture screen as shown in FIG. 1A.
While the present video signal has an aspect ratio of 4:3, a video signal having a wide aspect ratio of 16:9 (=1.78:1) has been proposed and a monitor receiver that can receive and reproduce such video signal is now commercially available on the market. Under the present condition, most video signals have an aspect ratio of 4:3 and a few video signals has an aspect ratio of 16:9. Therefore, when the video signal having an aspect ratio of 4:3 is supplied to the monitor receiver that receives and reproduces the video signal having an aspect ratio of 16:9, some suitable processing such as to display a reproduced picture of the video signal on the center of the picture screen or the like is carried out, as shown in FIG. 1B.
When the above-mentioned monitor receiver receives and reproduces the above letter box-type video signal, a reproduced picture is presented as shown in FIG. 1C, wherein the letter box type video signal is displayed in the range having an aspect ratio of 4:3 displayed on the center of the picture screen having an aspect ratio of 16:9. That is, black portions (shown hatched) are provided on the upper, lower, right and left portions of the picture screen. To remove this drawback, it is proposed that the monitor receiver includes means for enlarging a reproduced picture. Then, the viewer controls a magnification in a manual fashion so that the reproduced picture is displayed on the whole picture screen.
As a means for enlarging a reproduced picture, there are employed a method for enlarging a reproduced picture by using an image memory according to an image processing such as an interpolation or the like and a method for enlarging a reproduced picture by enlarging deflection widths in the horizontal and vertical directions. In this case, the reproduced picture is enlarged such that the upper and lower portions of the reproduced picture coincide with the upper and lower portions of the picture screen. Accordingly, a reproduced picture of European Vista Vision size having an aspect ratio smaller than the aspect ratio of 16:9 is enlarged such that the black portions are left on the right and left portions of the picture screen. Further, the reproduced pictures of American Vista Vision size, of 70mm-size and of Cinema Scope size, each having aspect ratios larger than the aspect ratio of 16:9, are enlarged such that the right and left portions of the reproduced picture are cut down slightly.
According to the aforesaid method in which the viewer controls a magnification in a manual fashion, the viewer is annoyed by cumbersome operation. Also, when a video signal having a different aspect ratio is received and reproduced, if the viewer does not notice that the last magnification control operation is still effective, there is then the risk that a picture will not be received and reproduced correctly. Furthermore, U.S. Pat. No. 4,951,149 describes a method for enlarging a picture by adjusting deflection voltages both in the horizontal and vertical directions. This previously-proposed method imposes a problem such that a resolution of an enlarged reproduced picture is deteriorated considerably.